The external-cavity diode laser is advantageous in terms of low noise, high side-mode suppression ratio, high temperature stability, simple structure, and low cost, which has been the preferred scheme to realize wide-tuning and narrow-linewidth characteristics. Thus, it has been widely used in optical communication, lidar, environmental monitoring, spectral analysis, optical coherence tomography, and other frontier fields. Herein, we introduce the technical scheme and review the development status of wide-tuning and narrow-linewidth external-cavity diode lasers in detail. Primarily, the structure, working principles, and performance characteristics of external-cavity diode lasers are deeply analyzed according to different structures. The structural characteristics, key technologies, optical performance and application fields of state-of-theart studies in recent years are discussed. Finally, the challenges and potential development prospects of wide-tuning and narrow-linewidth external-cavity diode lasers are analyzed and discussed.

A novel thermal-optical phase modulation structure based on polymer/silica hybrid waveguide is proposed. Patterned graphene strip is introduced as electric nanoheater in the structure. Finite element method simulation is performed on both thermal and optical field analysis. Results show that response speed is improved by a factor of three and power consumption is reduced by half, in comparison with conventional state-of-art polymer-based phase shifter. This proposed structure is compatible with current complementary metaloxide-semiconductor power supply standard and has very large design robustness. It shows great application potential on low-power optical switch, modulator and polymer thermaloptical phase arrays.

Intestinal ischemia/reperfusion (II/R) injury is a common life-threatening complication with high morbidity and mortality. Chebulae Fructus Immaturus, the unripe fruit of Terminalia chebula Retz., also known as “Xiqingguo” or “Tibet Olive” in China, has been widely used in traditional Tibetan medicine throughout history. The phenolic acids’ extract of Chebulae Fructus Immaturus (XQG for short) has exhibited strong antioxidative, anti-inflammation, anti-apoptosis, and antibacterial activities. However, whether XQG can effectively ameliorate II/R injuries remains to be clarified. Our results showed that XQG could effectively alleviate II/R-induced intestinal morphological damage and intestinal barrier injury by decreasing the oxidative stress, inflammatory response, and cell death. Transcriptomic analysis further revealed that the main action mechanism of XQG protecting against II/R injury was involved in activating PPARα and inhibiting the NF-κB-signaling pathway. Our study suggests the potential usage of XQG as a new candidate to alleviate II/R injury.